Vacuum bag-less composite repair systems and methods

ABSTRACT

Described are methods and systems for repair of composite components without the use of vacuum bagging. The systems described herein include a composite repair structure with a repair laminate and a film sealant. The film sealant covers the repair laminate to prevent intrusion of air and other volatiles during bonding of the composite repair structure to the composite being repaired. As the film sealant prevents intrusion of air and other volatiles, the composite repair structure can be bonded to the structure to be repaired without the use of a vacuum bag. Thus, vehicle components can be repaired without disassembly from the vehicle.

BACKGROUND

Current composite repair processes require vacuum bags for repair ofcomposite laminates. However, use of vacuum bags adds complication tothe repair process. For example, in certain processes, the vacuum bagmust pass a vacuum leak check and maintain a minimum vacuum to ensurethat the vacuum bag provides adequate sealing. These vacuum requirementsare problematic as they cannot be met in many repair instances. Forexample, it is often difficult or impossible for vacuum bags used torepair composite propulsion structures, such as acoustic inlets andthrust reverser inner walls, with sound attenuating features, such asperforated composite face sheets and slotted honey comb cores, to passthese requirements. Such perforations or slotted features are difficultor impossible to seal and create a large number of possible leak paths.

To overcome this problem, repair of these propulsion structures requirethe structures to be removed from the aircraft and disassembled so thatthey can be completely enclosed in a giant vacuum bag. The number oflabor hours required to disassemble and then reassemble the part addsdays to the repair process, complicates the repair process, and requiresspecialized equipment and facilities, increasing the cost of repair andthe downtime of aircraft.

SUMMARY

Described are methods and systems for repair of composite componentswithout the use of vacuum bagging. Systems described herein allow forrepair of a structure, such as a vehicle structure, with a compositerepair patch known as a composite repair structure. The composite repairstructure can be bonded to a vehicle structure through the applicationof heat and positive pressure. To prevent air and volatiles fromintruding during bonding of the composite repair structure to thevehicle structure, the composite repair structure includes a filmsealant disposed over a repair laminate. As the film sealant preventsintrusion of air and other volatiles, the composite repair structure canbe cured and bonded to the structure to be repaired without the use of avacuum bag.

Illustrative, non-exclusive examples of inventive features according topresent disclosure are described in following enumerated paragraphs:

A1. Method 400 comprising:

forming (step 420) composite repair structure 200, wherein compositerepair structure 200 comprises repair laminate 206, and wherein forming(step 420) composite repair structure 200 comprises applying (step 404)film sealant 202 to first surface 204A of repair laminate 206;

coupling (step 410) composite repair structure 200 to vehicle structure120; and

curing and/or bonding (step 422) composite repair structure 200 tovehicle structure 120 by providing (step 416) positive pressure 320 tocomposite repair structure 200 coupled to vehicle structure 120, whereinfilm sealant 202 prevents air intrusion into repair laminate 206 duringcuring and/or bonding of composite repair structure 200 to vehiclestructure 120.

A2. Method 400 of paragraph A1, wherein curing and/or bonding (step 422)composite repair structure 200 to vehicle structure 120 furthercomprises providing (step 414) heat to composite repair structure 200coupled to vehicle structure 120.

A3. Method 400 of any one of paragraphs A1-A2, wherein film sealant 202is further applied (step 404) to second surface 204B opposite firstsurface 204A of repair laminate 206.

A4. Method 400 of any one of paragraphs A1-A3, wherein positive pressure320 is provided (step 416) without vacuum.

A5. Method 400 of any one of paragraphs A1-A4, wherein forming 420composite repair structure 200 further comprises:

applying (step 405) heat to composite repair structure 200 to degascomposite repair structure 200;

disposing composite repair structure 200 within chamber 500, whereinchamber 500 is configured to minimize compaction on composite repairstructure 200 when a vacuum is present within chamber 500; and

providing (step 406) vacuum within chamber 500.

A6. Method 400 of any one of paragraphs A1-A5, wherein repair laminate206 comprises resin 208, and wherein film sealant 202 has a higherminimum viscosity temperature than resin 208.

A7. Method 400 of any one of paragraphs A1-A6, wherein forming (step420) composite repair structure 200 further comprises laying (step 402)up a plurality of repair laminate 206.

A8. Method 400 of any one of paragraphs A1-A7, wherein curing and/orbonding (step 422) composite repair structure 200 further comprisesprepping (step 412) composite repair structure 200 after coupling (step410) composite repair structure 200 to vehicle structure 120, whereinprepping (step 412) composite repair structure 200 comprises:

applying release film 312 to a portion of composite repair structure200; and applying compliance layer 314 to the portion of compositerepair structure 200.

A9. Method 400 of any one of paragraphs A1-A8, wherein coupling thecomposite repair structure 200 to vehicle structure 120 comprises:

applying film adhesive 310 to portion 322 of vehicle structure 120;

coupling composite repair structure 200 to film adhesive 310;

disposing compaction bag 318 over composite repair structure 200 aftercomposite repair structure 200 has been coupled to film adhesive 310 toseat composite repair structure 200; and

removing compaction bag 318.

Alternatively, venting compaction hag 318 to atmosphere to remove vacuumfrom repair laminate 206 and applying positive pressure and heat throughor over compaction bag 318.

A10. Method 400 of any one of paragraphs A1-A9, wherein composite repairstructure 200 is coupled to vehicle structure 120 when vehicle structure120 is coupled to vehicle 100.

A11. A composite repair structure 200, composite repair structure 200comprising:

a repair laminate 206; and

a film sealant 202 disposed on a first surface 204A of the repairlaminate 206, wherein the composite repair structure 200 is configuredto be cured and/or bonded to a vehicle structure 120 through positivepressure 320 applied to the composite repair structure 200 when thecomposite repair structure 200 is coupled to the vehicle structure 120,and wherein the film sealant 202 prevents air intrusion into the repairlaminate 206 during curing and/or bonding of the composite repairstructure 200 to the vehicle structure 120.

A12. Composite repair structure 200 of paragraph A11, wherein the filmsealant 202 is further disposed on a second surface 204B opposite thefirst surface 204A of the repair laminate 206.

A13. Composite repair structure 200 of any one of paragraphs A11-A12,wherein the repair laminate 206 comprises a resin 208, and wherein thefilm sealant 202 has a higher minimum viscosity temperature than theresin 208.

A14. A method 420 of forming composite repair structure 200 of any oneof paragraphs A11-A13, the method comprising:

laying up 402 repair laminate 206;

applying 405 heat to repair laminate 206 to degas repair laminate 206;and applying 404 film sealant 202 to first surface 204A.

A15. Method 420 of paragraph A14, wherein applying 405 heat to repairlaminate 206 to degas repair laminate 206 comprises:

reducing a viscosity of resin 208 of repair laminate 206; and

covering fibers of repair laminate 206 with the resin 208.

A16. An apparatus comprising:

a vehicle structure 120; and

a composite repair structure 200 bonded to a portion of the vehiclestructure the composite repair structure 200 comprising:

-   -   a repair laminate 206; and    -   a film sealant 202 disposed on a first surface 204A of the        repair laminate 206, wherein the film sealant 202 is configured        to prevents air intrusion into the repair laminate 206 during        curing and/or bonding of the composite repair structure 200 to        the vehicle structure 120.

A17. The apparatus of paragraph A16, wherein the film sealant 202 isfurther disposed on a second surface 204B opposite the first surface204A of the repair laminate 206.

A18. The apparatus of any one of paragraphs A16-A17, wherein the repairlaminate 206 comprises a resin 208, and wherein the film sealant 202 hasa higher minimum viscosity temperature than the resin 208.

A19. The apparatus of any one of paragraphs A16-A18, the apparatusfurther comprising:

a release film 312 disposed on the portion of the vehicle structure 120;

a compliance layer 314 disposed on the portion of the vehicle structure120; and

a weight, pneumatic bladder, or actuator coupled to the composite repairstructure 200 to apply positive pressure 320 on the composite repairstructure 200.

A20. The apparatus of any one of paragraphs A16-A19, wherein the vehiclestructure 120 is a propulsor, a fuselage, or a wing.

These and other examples are described further below with reference tofigures.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, whichillustrate various examples.

FIG. 1 illustrates a vehicle with composite structures, in accordancewith some examples.

FIG. 2 illustrates a cross-sectional representation of a compositerepair structure, in accordance with some examples.

FIG. 3A illustrates a cross-sectional representation of a step in atechnique of composite repair utilizing the composite repair structureof FIG. 2 , in accordance with some examples.

FIG. 3B illustrates a cross-sectional representation of another step inthe technique of composite repair utilizing the composite repairstructure of FIG. 3A, in accordance with some examples.

FIG. 4 is a process flowchart corresponding to a method of compositerepair, in accordance with some examples.

FIG. 5A illustrates a cross-sectional representation of a double vacuumdebulk chamber, in accordance with some examples.

FIG. 5B illustrates a cross-sectional representation of a lower bag ofthe double vacuum debulk chamber of FIG. 5A, in accordance with someexamples.

FIG. 6A illustrates a flow chart of an example of an aircraft productionand service methodology, in accordance with some examples.

FIG. 6B illustrates a block diagram of an example of a vehicle, inaccordance with some examples.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the presented concepts. Thepresented concepts may be practiced without some, or all, of thesespecific details. In other instances, well known process operations havenot been described in detail to avoid unnecessarily obscuring thedescribed concepts. While some concepts will be described with thespecific examples, it will be understood that these examples are notintended to be limiting.

Introduction

Currently, technique to repair certain composite vehicle components,such as nacelles or propulsor inlets with noise attenuation features, isto remove the components from the vehicle and strip down the componentsbefore repairing with a vacuum bag. Even minor repairs require removalof these very large and expensive parts from the vehicles and placementof these parts within vacuum bags. Furthermore, disassembly (fastenerremovals, separating surface sealed components, removal of rivets, andother such disassembly steps) and subsequent handling of such largeunwieldy structures greatly increase the risk of incidental damage tothe part. Thus, such techniques require a large number of hours andgreat care to perform and add complication and expense to the repairprocess.

An example of a vehicle with such structures is shown in FIG. 1 . FIG. 1illustrates a vehicle with composite structures, in accordance with someexamples. FIG. 1 illustrates a vehicle 100 that can be a fixed wingaircraft. In other examples, the systems and techniques described hereincan be used to repair composites and structures of other types ofvehicles such as other types of aircraft (e.g., helicopters, spacecraft,rockets, and other aircraft), automobiles, ships, submarines, and othersuch vehicles.

Vehicle 100 includes a plurality of vehicle structures 120. In variousexamples, vehicle structures 120 can be different portions of vehicle100. For example, for the aircraft shown in FIG. 1 , vehicle structures120 can be a fuselage, a wing (e.g., a fixed portion of the wing or aflap or other movable portion), an aircraft propulsor (e.g., a nacelleor inlet of the aircraft propulsor), an empennage, or another structureof the aircraft. Various examples of vehicle structures 120 can be madeof composites such as one or more of fiberglass, carbon fiber, Kevlar®,and other such composites.

Examples of Structures for No Vacuum Bag Composite Repair

FIG. 2 illustrates a cross-sectional representation of a compositerepair structure, in accordance with some examples. FIG. 2 illustrates acomposite repair structure 200 for use in repairing (e.g., patching)composite structures such as vehicle structures 120 described herein. Insome examples, composite repair structure 200 is used to repaircomposite vehicle structures by, for example, coupling or bonding to thecomposite vehicle structure. For example, bonding of composite repairstructure 200 to such vehicle structures is accomplished throughapplication of positive pressure and heat and without the use of vacuumbagging. Composite repair structure 200 includes film sealant 202A and202B and repair laminate 206A-C.

Repair laminate 206A-C includes composite plies such as one or more ofcarbon fiber plies, fiberglass plies, Kevlar® plies, and other suchcomposite plies. In certain examples, layers of repair laminate is laidon top of each other to form the core repair structure. Though theexample shown in FIG. 2 illustrates a composite repair structure 200that includes three layers of repair laminate 206A-C, other examples caninclude any number of layers of repair laminate.

Repair laminate 206A-C is bonded together with resin 208 or another typeof polymer. Resin 208 penetrates through the fibers of repair laminate206A-C to solidify repair laminate 206A-C. In certain examples, repairlaminate 206A-C is, for example, pre-impregnated (pre-preg) compositeswith resin 208 pre-impregnated within repair laminate 206A-C. Thepre-preg is heated during production to liquefy resin 208, allowingresin 208 to penetrate the fibers of repair laminate 206A-C and displaceany air within the fibers. As any air remaining within repair laminate206A-C can weaken composite repair structure 200, repair laminate 206A-Cis fully penetrated with resin 208 to fully displace any air during theproduction process. Fully displacing the air maximizes the strength ofcomposite repair structure 200.

Repair structures are typically heated to bond the repair structures tovehicle structures. As repair structures are heated, resin will returnto a liquid state. In conventional repair processes, containing thevehicle structure and repair structure within a vacuum bag preventssubsequent air intrusion while the resin is in the liquid state.However, without vacuum bagging, air and other volatiles will intrudeinto the resin and thus the repair laminate during conventional repairprocesses, causing porosity and weakening the structure.

Film sealant 202A and 202B is disposed on surfaces of repair laminate206A-C. Thus, for example, film sealant 202A is disposed on a firstsurface of repair laminate 206A-C and film sealant 202B is disposed on asecond surface of repair laminate 206A-C opposite the first surface. Invarious examples, film sealant is disposed on a variety of portions ofrepair laminate 206A-C or on all outer surfaces of repair laminate206A-C. Film sealant (including film sealant 202A and 202B) prevents airintrusion to the repair laminate during bonding of composite repairstructure 200 to vehicle structure 120. As the film sealant prevents airintrusion to the repair laminate, composite repair structure 200 canaccordingly be bonded to a vehicle structure without the use of vacuumor vacuum bag.

In certain examples, to prevent intrusion of air and other volatiles,film sealant 202A and 202B has a higher minimum viscosity temperaturethan that of resin 208. Thus, film sealant 202A and 202B function aseffective air barriers when the resin is most vulnerable to airintrusion (e.g., when the resin is at its lowest viscosity, such as whencomposite repair structure 200 is heated to bond composite repairstructure 200 to vehicle structure 120). During the repair process, asthe temperature increases due to heating, resin 208 then subsequentlygels (e.g., the viscosity of resin 208 increases) to the point where airno longer or only minimally penetrates resin 208 and/or repair laminate206A-C. At this increased temperature, viscosity of film sealant 202Aand 202B can then be at its minimum level. Film sealant 202A and 202Bcan thus comingle with resin 208 and any adhesives on the vehiclestructure, creating a strong and durable bond.

As such, film sealant 202A and 202B, as well as any other film sealantdisposed on the surface of composite repair structure 200, allow forcomposite repair structure 200 to be bonded to vehicle structure 120without the use of a vacuum bag while still preventing air and volatilesintrusion into resin 208.

Various steps of vacuum bag-less repair techniques are now illustratedherein. FIG. 3A illustrates a cross-sectional representation of a stepin a technique of composite repair utilizing the composite repairstructure of FIG. 2 , in accordance with some examples. FIG. 3Aillustrates an assembly 300A detailing a step when composite repairstructure 200 is coupled to vehicle structure 120. Assembly 300Aillustrates a step where composite repair structure 200 is positioned onvehicle structure 120 (e.g., to prepare for bonding during a patchrepair).

Thus, composite repair structure 200 is placed over portion 322 ofvehicle structure 120. In certain examples, portion 322 is a portion ofvehicle structure 120 that requires repair. Film adhesive 310 is placedon portion 322. Film adhesive 310 is placed between portion 322 andcomposite repair structure 200. Film adhesive 310 encourages the bondingof composite repair structure 200 to portion 322.

Compaction bag 318 can optionally be placed over and/or containcomposite repair structure 200 to provide a vacuum to properly seatcomposite repair structure 200 over portion 322. In certain examples,compaction bag 318 does not meet the typical vacuum requirements of avacuum bag application. Instead, compaction bag 318 can be a temporarycompaction bag for seating composite repair structure 200. In certainexamples, a release film 312 is disposed between composite repairstructure 200 and compaction bag 318 to promote release of compactionbag 318 from composite repair structure 200 once composite repairstructure 200 is seated. After use, compaction bag 318 can be discarded.Alternatively, in some examples, compaction bag 318 is vented toatmosphere to remove vacuum from repair laminate 206 and positivepressure and/or heat is applied through or over compaction bag 318.

FIG. 3B illustrates a cross-sectional representation of another step inthe technique of composite repair utilizing the composite repairstructure of FIG. 3A, in accordance with some examples. FIG. 313illustrates an assembly 300B detailing a step when composite repairstructure 200 is bonded to vehicle structure 120.

In certain examples, after composite repair structure 200 is coupled tovehicle structure 120, release film 312 is disposed over compositerepair structure 200. A compliance layer 314 is then applied overrelease film 312. In certain such examples, compliance layer is a thin(e.g., 0.5 inch or thinner), low durometer, thermally conductivematerial that will conform to the shape of the repair (e.g., ofcomposite repair structure 200) to provide better load transfer tocomposite repair structure 200.

Heating blanket 316 is disposed over compliance layer 314. Heatingblanket 316 is configured to provide heat to composite repair structure200 and/or portion 322 to allow composite repair structure 200 to bondto portion 322. Additionally, in certain examples, a layer of siliconerubber foam (e.g., between 0.25 to 2 inches thick) is placed overheating blanket 316 to thermally isolate the repair from items thatprovide positive pressure 320 to the repair.

Heating blanket 316 provides heat to increase the temperature ofcomposite repair structure 200 and/or vehicle structure 120. Certainexamples of heating blanket 316 are configured to heat composite repairstructure 200 to a variety of different temperatures.

Thus, for such examples, heating blanket 316 increases the temperatureof composite repair structure 200 through a period of time bycontinuously providing heat to composite repair structure 200. As such,composite repair structure 200 is heated through a period of time. Forexample, composite repair structure 200 is first heated to a firsttemperature whereby resin 208 is more viscous or liquid to aid inbonding with vehicle structure 120.

As the temperature increases, resin 208 begins to harden while filmsealant 202A and 202B becomes more viscous or liquid. The decreasingviscosity of film sealant 202A and 202B allows film sealant 202A and202B to comingle with resin 208 and any adhesives of vehicle structure120, creating a strong and durable bond.

In certain examples, positive pressure 320 is further provided to createa strong and durable bond. Positive pressure as described herein denotesany sort of pressure applied. For example, positive pressure includespressure provided by weight (e.g., shot or sand bags), a machine (e.g.,an actuator, a clamp, press, or other machine), a pneumatic bladder orthrough other techniques to provide pressure. In some examples, positivepressure 320 is any amount of pressure, including pressure of between 1to 10 pounds per square inch (psi) applied to composite repair structure200. Positive pressure 320 further bonds composite repair structure 200to vehicle structure 120 by allowing resin 208, film sealant 202A and/or202B, and/or any adhesives of vehicle structure 120 to comingle and/ormix to form a strong bond.

Examples of Method for No Vacuum Bag Composite Repair

FIG. 4 is a process flowchart corresponding to a method of compositerepair, in accordance with some examples. Various operations of method400 of FIG. 4 are executed using systems and apparatus described herein.Steps 402 to 406 describe forming 420 of composite repair structure 200,while steps 408 to 418 describe the repair of a vehicle structure withthe composite repair structure.

In step 402, repair laminate 206 is laid up. In certain examples, repairlaminate 206 includes a plurality of composite plies (e.g., carbon fibercomposite plies). The plies laid up in step 402 form repair laminate206. In step 404, film sealant 202 is applied to the outer surfaces ofrepair laminate 206. Film sealant 202 prevents air and volatileintrusion into resin 208 and/or repair laminate 206 during vacuumbag-less bonding to vehicle structure 120.

In step 406, composite repair structure 200 is disposed within a vacuumchamber and vacuum is provided to composite repair structure 200. Suchvacuum is be applied, for example, in a double vacuum debulk chamber (asdescribed in FIGS. 5A and 5B). Double vacuum debulk allows for removalof volatiles from repair laminate 206 without the use of an autoclave.Double vacuum debulk allows for application of heat and vacuum tocomposite repair structure 200 without subjecting composite repairstructure 200 to vacuum compaction (e.g., from atmospheric pressureacting on a vacuum hag).

Heat is applied during one or more of steps 402, 404, and 406 in step405.

Heating of film sealant 202, repair laminate 206, resin 208, and/oranother portion of composite repair structure 200 to varioustemperatures decreases resin and/or sealant viscosity and/or partiallycures the resin and/or sealant to partially cure composite repairstructure 200. In certain examples, heat is applied during both steps402 and 404 to, for example, allow venting or degassing of entrapped airand gases from repair laminate 206 as well as, potentially, curing ofrepair laminate 206 in step 402 and curing of film sealant 202 in step404, respectively. In other examples, heat is applied during step 406 tofirst decrease viscosity to allow venting of air from repair laminate206 before then partially curing both repair laminate 206 and filmsealant 202 simultaneously.

As such, after step 402, 404, 405, and/or 406, composite repairstructure 200 is formed to be in a pliant intermediate state. Such anintermediate state allows for composite repair structure 200 to becoupled to and conform to a surface of a vehicle structure. Once coupledto the vehicle structure, heat and positive pressure is then applied tofully cure composite repair structure 200 into a solid state, asdescribed herein.

Thus, after composite repair structure 200 has been formed, compositerepair structure 200 is used to repair a vehicle structure in steps 408to 418. In step 408, the surface of a portion of vehicle structure 120to be repaired is prepped. Prepping includes, for example, applying filmadhesive 310 over the surface of vehicle structure 120, cleaning andsanding of the surface of vehicle structure 120 (e.g., to promote betteradhesion), and/or other such preparation activities.

After vehicle structure 120 has been prepped in step 408, compositerepair structure 200 is coupled to vehicle structure 120 in step 410,according to techniques described herein. Thus, for example, compositerepair structure 200 is positioned over a portion of vehicle structure120 to be repaired. In certain examples, compaction bag 318 is also bedisposed over composite repair structure 200 to seat composite repairstructure 200 over the proper portion of vehicle structure 120.

Composite repair structure 200 is thus be properly positioned overvehicle structure 120. Afterwards, composite repair structure 200 isthen cured and/or bonded 422 to vehicle structure 120 or a portiontherefore in steps 412 to 416. Curing and/or bonding 422 includes, forexample, prepping of composite repair structure 200 in step 412.Prepping of composite repair structure 200 includes, for example,applying release film 312 and/or disposing compliance layer 314 overcomposite repair structure 200.

Heat and positive pressure is then applied in steps 414 and 416,respectively, to cure and/or bond 422 composite repair structure 200 tovehicle structure 120. In certain examples, composite repair structure200 and vehicle structure 120 is co-bonded. That is, composite repairstructure 200 (e.g., repair laminate 206) is cured while simultaneouslybonded to vehicle structure 120 (which is a second cured laminate).

In step 416, positive pressure is applied through the techniquesdescribed herein (e.g., mechanically, through weight, through forceexerted on the surface of composite repair structure 200, or otheranother technique). In step 414, heat is applied to composite repairstructure 200 and/or vehicle structure 120 through, for example, heatemitted by heating blanket 316, emitted by heating lamps, emitted byheat guns, or from another source. Composite repair structure 200 isthus be bonded to vehicle structure 120. The repair is then be finalizedin step 418 by, for example, surfacing (e.g., smoothing) and finishing(e.g., painting) of the repair.

Manufacturing Chamber for the Composite Repair Structure

As described herein, composite repair structure 200 is at leastpartially formed in a double vacuum debulk chamber. FIG. 5A illustratesa cross-sectional representation of a double vacuum debulk chamber, inaccordance with some examples. Double vacuum debulk allows for removalof volatiles from repair laminate 206, after repair laminate 206 hasbeen laid up, without the use of an autoclave by applying heat andvacuum while forming composite repair structure 200 without subjectingcomposite repair structure 200 to vacuum compaction.

Double vacuum debulk chamber 500 shown in FIG. 5A includes an upperbagging film 502, a breather cloth 504, a hardback 506, vacuum probes508, a breather 510, and a lower bag 512. Composite repair structure 200is disposed within lower bag 512 during forming thereof. Upper baggingfilm 502 is a vacuum bag and is configured to contain a vacuum. Vacuumprobes 508 allow for adjustment of vacuum within upper bagging film 502.

Hardback 506 is disposed over lower bag 512 and, in certain examples, isa rigid or semi-rigid structure. In certain examples, hardback 506prevents upper bagging film 502 from imparting force on lower bag 512when there is a vacuum within upper bagging film 502. As vacuum isgenerated within upper bagging film 502, hardback 506 preventscompaction force from the vacuum within upper bagging film 502 frombeing imparted onto composite repair structure 200 (contained withinlower bag 512). Thus, hardback 506 allows composite repair structure 200to be formed within a vacuum, but without being subjected to compactionforces from the vacuum.

FIG. 5B illustrates a cross-sectional representation of a lower bag ofthe double vacuum debulk chamber of FIG. 5A, in accordance with someexamples. FIG. 5B further illustrates lower bag 512. Lower bag 512 shownin FIG. 5B includes a lower bagging film 514, a breather 516, nonporousrelease film 518 and 524, a bleeder 520, porous or perforated releasefilm or fabric 522, a thermally conductive sheet 526, heating element528, a breather 530, and electrical circuitry 532. In the example shown,composite repair structure 200 is disposed within the layers of porousor perforated release film or fabric 522.

Electrical circuitry 532 provides electrical power to heating element528. Heating element 528 is, for example, a heating blanket. Heatingelement 528 generates heat from the provided electrical power. The heatis then used to reduce the resin viscosity of the composite repairstructure 200. In some examples, preventing air compaction while repairlaminate 206 is formed (e.g., when vacuum is generated and heat isprovided by heating element 528) allows for the extraction of gases andother volatiles from the fibers of repair laminate 206. The reducedviscosity of resin 208 allows for resin 208 to flow into the volumepreviously occupied by the gases and volatiles. In certain examples,resin 208 can then occupy most or all of the space around the fibers ofrepair laminate 206.

In certain examples, after extraction of the gases and volatiles,hardback 506 is vented to atmosphere. Atmospheric pressure is then ableto impart a compaction force on lower bag 512 and, thus, compositerepair structure 200 to form composite repair structure 200 to the finalshape. By applying compaction forces only after the gases and volatilesare extracted, the techniques described herein allow for venting oftrapping of gases and volatiles and, thus, avoid trapping of such gasesand volatiles within composite repair structure 200. Such a techniqueproduces a stronger composite repair structure 200. Afterwards,composite repair structure 200 is removed from double vacuum debulkchamber 500 and ready to bond to a vehicle structure.

Vehicle Examples

While the systems, apparatus, and methods disclosed above have beendescribed with reference to airplanes and the aerospace industry, itwill be appreciated that the examples disclosed herein is applicable toother contexts as well, such as automotive, railroad, and othermechanical and vehicular contexts. Accordingly, examples of thedisclosure is described in the context of an airplane manufacturing andservice method 600 as shown in FIG. 6A and vehicle 100 as shown in FIG.6B in applicable to such other contexts.

FIG. 6A illustrates a flow chart of an example of a vehicle productionand service methodology, in accordance with some examples. In someexamples, during pre-production, method 600 includes the specificationand design 604 of vehicle 100 (e.g., an aircraft as shown in FIG. 1 )and material procurement 606. During production, component andsubassembly manufacturing 608 and system integration 610 of vehicle 100takes place. Thereafter, vehicle 100 goes through certification anddelivery 612 in order to be placed in service 614. While in service by acustomer, the vehicle 100 is scheduled for routine maintenance andservice 616 (e.g., modification, reconfiguration, refurbishment, and soon).

In certain examples, each of the processes of method 600 is performed orcarried out by a system integrator, a third party, and/or an operator(e.g., a customer). For the purposes of this description, a systemintegrator includes any number of airplane manufacturers andmajor-system subcontractors; a third party includes any number ofvenders, subcontractors, and suppliers; and an operator can be anairline, leasing company, military entity, service organization, and soon.

FIG. 6B illustrates a block diagram of an example of a vehicle, inaccordance with some examples. As shown in FIG. 6B, the vehicle 100(e.g., an aircraft) produced by method 600 includes airframe 618 withplurality of systems 620, and interior 622, Examples of systems 620include one or more of propulsion system 624, electrical system 626,hydraulic system 628, and environmental system 630. In various examples,other systems are also included within vehicle 100. Although anaerospace example is shown, the principles of the embodiments disclosedherein is applicable to other industries, such as the automotiveindustry.

Conclusion

Although foregoing concepts have been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within scope of appendedclaims. It should be noted that there are many alternative ways ofimplementing processes, systems, and apparatuses. Accordingly, presentexamples are to be considered as illustrative and not restrictive.

The invention claimed is:
 1. A method comprising: forming a compositerepair structure, wherein the composite repair structure comprises arepair laminate, wherein the repair laminate comprises a resin with aresin minimum viscosity temperature, wherein the forming the compositerepair structure comprises applying a film sealant with a sealantminimum viscosity temperature to a first surface of the repair laminate,wherein the sealant minimum viscosity temperature is higher than theresin minimum viscosity temperature, and wherein the sealant minimumviscosity temperature is a temperature where the resin at leastpartially gels; coupling the composite repair structure to a vehiclestructure; and curing and/or bonding the composite repair structure tothe vehicle structure by: providing a positive pressure to the compositerepair structure coupled to the vehicle structure; and increasing thetemperature of the resin from the resin minimum viscosity temperature,where the film sealant prevents air intrusion into the repair laminate,to the sealant minimum viscosity temperature, where the at leastpartially gelled resin prevents air intrusion.
 2. The method of claim 1,wherein the curing and/or bonding the composite repair structure furthercomprises prepping the composite repair structure after coupling thecomposite repair structure to the vehicle structure, wherein theprepping the composite repair structure comprises: applying a releasefilm to a portion of the composite repair structure; and applying acompliance layer to the portion of the composite repair structure. 3.The method of claim 2, wherein a weight is coupled to the compositerepair structure to apply positive pressure on the composite repairstructure.
 4. The method of claim 1, wherein forming the compositerepair structure further comprises: laying up the repair laminate;applying heat to the repair laminate to degas the repair laminate; andapplying the film sealant to the first surface.
 5. The method of claim4, wherein the applying the heat to the repair laminate to degas therepair laminate comprises: reducing a viscosity of a resin of the repairlaminate; and covering fibers of the repair laminate with the resin. 6.The method of claim 1, wherein the vehicle structure comprises acomposite material.
 7. The method of claim 6, wherein the compositematerial comprises one or more of fiberglass, carbon fiber, Kevlar®, andother such composite materials.
 8. The method of claim 1, wherein thecuring and/or bonding the composite repair structure to the vehiclestructure further comprises providing heat to the composite repairstructure coupled to the vehicle structure.
 9. The method of claim 1,wherein the film sealant is further applied to a second surface oppositethe first surface of the repair laminate.
 10. The method of claim 1,wherein the positive pressure is provided without vacuum.
 11. The methodof claim 1, wherein the forming the composite repair structure furthercomprises: applying heat to the composite repair structure to degas thecomposite repair structure; disposing the composite repair structurewithin a chamber, wherein the chamber is configured to minimizecompaction on the composite repair structure when a vacuum is presentwithin the chamber; and providing the vacuum within the chamber.
 12. Themethod of claim 1, wherein at the sealant minimum viscosity temperature,the film sealant comingles with the resin.
 13. The method of claim 1,wherein the forming the composite repair structure further compriseslaying up a plurality of repair laminate.
 14. The method of claim 1,wherein the coupling the composite repair structure to the vehiclestructure comprises: applying film adhesive to a portion of the vehiclestructure; coupling the composite repair structure to the film adhesive;disposing a compaction bag over the composite repair structure after thecomposite repair structure has been coupled to the film adhesive to seatthe composite repair structure; and removing the compaction bag.
 15. Themethod of claim 1, wherein the composite repair structure is coupled tothe vehicle structure when the vehicle structure is coupled to avehicle.
 16. The method claim 1, wherein the film sealant is furtherdisposed on a second surface opposite the first surface of the repairlaminate.
 17. The method claim 1, wherein at the sealant minimumviscosity temperature, the film sealant comingles with the resin. 18.The method claim 1, wherein the film sealant is configured to preventair intrusion into the repair laminate during curing and/or bonding ofthe composite repair structure to the vehicle structure when at theresin minimum viscosity temperature.
 19. The method of claim 1, whereinthe vehicle structure is a propulsor, a fuselage, or a wing.
 20. Themethod of claim 1, wherein the vehicle structure is a fixed wing, amovable wing portion, or a movable flap structure of an aircraft.